Replacement prosthetic heart valves and methods of implantation

ABSTRACT

A replacement prosthetic heart valve for engagement with a structure of a previously implanted prosthetic heart valve. The replacement heart valve includes a stent structure including a generally tubular body portion with an interior area and a series of wire portions arranged in a mesh-like configuration, and at least one stent post engaging structure extending radially outwardly from the body portion for engaging with an outer surface of a stent post of the previously implanted prosthetic heart valve. The stent structure further includes at least two leaflets attached within the interior area of the tubular body portion of the stent structure.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional ApplicationNo. 60/901,787, filed Feb. 16, 2007, and titled “Replacement ProstheticHeart Valve Including Delivery System and Method of Implantation”, theentire contents of which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

The present invention relates to prosthetic heart valves. Moreparticularly, it relates to devices, methods, and delivery systems forpercutaneously implanting prosthetic heart valves.

BACKGROUND

Various types and configurations of prosthetic heart valves are used toreplace diseased natural human heart valves. The actual shape andconfiguration of any particular prosthetic heart valve is dependent tosome extent upon the valve being replaced (i.e., mitral valve, tricuspidvalve, aortic valve, or pulmonary valve). In general, the prostheticheart valve designs attempt to replicate the function of the valve beingreplaced and thus will include valve leaflet-like structures used witheither bioprostheses or mechanical heart valve prostheses.

As used throughout this specification a “prosthetic heart valve” isintended to encompass bioprosthetic heart valves having leaflets made ofa biological material (e.g., harvested porcine valve leaflets, or bovineor equine pericardial leaflets), along with synthetic leaflet materialsor other materials. These bioprosthetic heart valves typically include astent having a substantially circular base (or stent ring), around whichan annular suture material is disposed for suturing the prosthesis toheart tissue. The stent further typically includes at least two, buttypically three, support structures extending from the stent ring. Thesesupport structures are commonly referred to as stent posts or commissureposts. These posts typically are rigid yet somewhat flexible structuresextending from the stent ring, which are covered by a cloth-likematerial similar to that of the annular suture material. The stent orcommissure posts define the juncture between adjacent tissue orsynthetic leaflets otherwise secured thereto. Examples of bioprostheticheart valves are described in U.S. Pat. No. 4,106,129 (Carpentier etal.), and U.S. Pat. No. 5,037,434 (Lane), the entire disclosures ofwhich are incorporated herein by reference. These disclosures describe aconventional configuration of three leaflets, with one leaflet disposedbetween each pair of stent or commissure posts. Regardless of whether astent is provided, however, bioprosthetic heart valves are generallytubular so that when the leaflets are in an open position, an internalpassage is defined through which blood can flow.

The bioprosthetic heart valves further typically include a sewing ringor suture ring that provides a means for fixing the prosthetic heartvalve to the patient's native heart valve orifice tissue (e.g., nativeannulus or valvular rim) that is associated with the native heart valvebeing repaired or replaced. In particular, an exacting surgicalimplantation technique is traditionally employed whereby the heart isstopped (i.e., cardiopulmonary bypass) and opened, which is followed bysurgical removal of damaged or diseased natural valve structure. Aprosthetic heart valve can then be oriented within the native valvulararea, with the sewing ring being seated against or at the native annulusor valvular rim. Sutures are then used to affix the sewing ring to thenatural tissue. Obviously, the risks associated with this invasive typeof surgery are numerous, particularly when cardiopulmonary bypassprocedures are used.

A successfully implanted prosthetic heart valve will normally functionwithout problems for many years. In certain instances, however,deficiencies may become evident shortly after implant or within a fewyears, particularly in younger patients. Common functional deficienciesinclude the calcification of the prosthetic heart valve leaflets,stenosis, and prosthetic heart valve insufficiency. Under these andother circumstances, the prosthetic heart valve does not functionproperly and conventionally requires surgical removal and replacement.Surgical removal of such a previously implanted prosthetic heart valveentails the same invasive surgical intervention described above, coupledwith the need to remove the old prosthetic valve and implant a newprosthetic heart valve. In addition, the risk of mortality is oftenhigher when performing a second surgery in the same area of the body,particularly when performing heart-related surgeries. Anotherdisadvantage to this additional surgery is that the reopening of asternotomy has been known to have a relatively high risk of causing aninfection.

Thus, while these types of surgeries are well-accepted, the conventionalsurgical intervention described above is difficult to perform and canresult in patient injury or more severe complications. In fact, due tophysical weakness of a patient, implantation of a prosthetic heart valvevia the conventional surgical technique may be considered too high-riskor contra-indicated for certain patients. Further, removal of apreviously implanted prosthetic heart valve requires cutting of thesutures that secure the prosthesis to the native annulus/valvular rim,and attachment of a new sewing ring via stitching, which can furthercompromise the integrity of the valvular rim and lead to recoverycomplications, morbidity, and mortality.

Although not necessarily related to the specific prosthetic heart valvereplacement concerns described above, efforts have also been made todevise a prosthetic heart valve capable of being deliveredpercutaneously via transcatheter implantation, thereby avoiding thecomplications and risks associated with conventional surgicalintervention. For example, in U.S. Pat. No. 6,168,614 (Andersen et al.),a heart valve prosthesis is described for implantation in the body byuse of a catheter. The valve prosthesis consists of a support structurewith a tissue valve connected to it, whereby the support structure isdelivered in a collapsed state through a blood vessel and secured to adesired valve location with the support structure in an expanded state.

Other percutaneously-delivered prosthetic heart valves have beensuggested having a generally similar configuration, such as byBonhoeffer, P. et al., “Transcatheter Implantation of a Bovine Valve inPulmonary Position.” Circulation, 2002; 102:813-816, and by Cribier, A.et al. “Percutaneous Transcatheter Implantation of an Aortic ValveProsthesis for Calcific Aortic Stenosis.” Circulation, 2002;106:3006-3008, the disclosures of which are incorporated herein byreference. These techniques rely at least partially upon a frictionaltype of engagement between the expanded support structure and the nativetissue to maintain a position of the delivered prosthesis, although thestents can also become at least partially embedded in the surroundingtissue in response to the radial force provided by the stent and anyballoons used to expand the stent. Thus, with these transcathetertechniques, conventional sewing of the prosthetic heart valve to thepatient's native tissue is not necessary. Similarly, in an article byBonhoeffer, P. et al. titled “Percutaneous Insertion of the PulmonaryValve.” J Am Coll Cardiol, 2002; 39:1664-1669, the disclosure of whichis incorporated herein by reference, percutaneous delivery of abiological valve is described. The valve is sutured to an expandablestent within a previously implanted valved or non-valved conduit, or apreviously implanted valve. Again, radial expansion of the secondaryvalve stent is used for placing and maintaining the replacement valve.

Devices and methods have more recently been developed for percutaneouslyreplacing deficient, previously implanted prosthetic heart valves, whichare described, for example, in U.S. Patent Publication No. 2006/0052867(Revuelta et al.), the entire disclosure of which is incorporated hereinby reference. Other transcatheter technologies for deliveringreplacement valves are described in PCT Application Nos. WO2007/053243-A2, WO 2007/130537-A1, and WO 2007/081820-A1; United StatesPatent Application Publication Nos. 2005/0251251-A1, 2007/0043435-A1,and 2008/0004696-A1; and U.S. Pat. No. 7,195,641. However, a need existsfor additional prosthetic heart valves, delivery systems, and relatedmethods of implantation that are conducive to percutaneous delivery forreplacing a deficient, previously implanted bioprosthetic heart valve.

SUMMARY

The replacement valves of the invention are configured to providecomplimentary features that promote physical docking or connection ofthe replacement heart valve to a previously implanted prosthetic heartvalve, such as the aortic valve, mitral valve, pulmonic valve, andtricuspid valve. In some embodiments, the replacement heart valve andrelated methods of implantation of the invention utilize a previouslyimplanted prosthetic heart valve as a platform to facilitate mountingrelative to a native heart valve. Thus, the replacement heart valves ofthe invention are highly amenable to percutaneous delivery, althoughdelivery of the heart valves using an apical approach (either with orwithout cardiopulmonary bypass) is also contemplated. Further, in caseswhere a previously implanted prosthetic heart valve is beingfunctionally replaced, the deficient prosthetic heart valve need not bephysically removed from the patient. Thus, the prosthetic heart valveand related method of implantation of the present invention can be usedat any point during the “useful life” of a conventional prosthetic heartvalve. Further, the methodology associated with the present inventioncan be repeated multiple times, such that several prosthetic heartvalves of the present invention can be mounted on top of or within oneanother, if necessary or desired.

The replacement heart valves of the invention each include a stent towhich a valve structure is attached. The stents of the invention includea wide variety of structures and features that can be used alone or incombination with features of other stents of the invention. Inparticular, these stents provide a number of different docking and/oranchoring structures that cooperate with the structure of a previouslyimplanted prosthetic heart valve, and are conducive to percutaneousdelivery thereof. Many of the structures are thus compressible to arelatively small diameter for percutaneous delivery to the heart of thepatient, and then are expandable either via removal of externalcompressive forces (e.g., self-expanding stents), or through applicationof an outward radial force (e.g., balloon expandable stents). In afurther alternative, some portions of a stent may be self-expandingwhile other portions of the same stent are expandable throughapplication of an externally applied force.

Insertion or implantation of the replacement heart valves of theinvention can be accomplished using delivery systems that can maintainthe stent structures in their compressed state during their insertionand allow or cause all or specific features of the stent structures toexpand once they are in their desired location. In addition, some stentsof the invention can further include features that allow them to beretrieved for removal or relocation thereof after they have beendeployed from the stent delivery systems. The methods may includeimplantation of the stent structures using either an antegrade orretrograde approach. Further, in many of the delivery approaches of theinvention, the stent structure is rotatable in vivo to allow the stentstructure to be positioned in a desired orientation.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further explained with reference to theappended Figures, wherein like structure is referred to by like numeralsthroughout the several views, and wherein:

FIG. 1 is a perspective view of a prosthetic heart valve with a stent ofa replacement prosthetic heart valve of the invention positionedtherein;

FIG. 2 is a top view of the stent of FIG. 1 as positioned relative tothe outflow end of a prosthetic heart valve;

FIG. 3 is a bottom view of the stent of FIG. 1 as positioned relative tothe inflow end of a prosthetic heart valve;

FIG. 4 is a perspective view of the stent of FIG. 1 as it can be used asa component of a replacement prosthetic heart valve;

FIG. 5 is a perspective view of another embodiment of a stent of theinvention as it can be used as a component of a replacement prostheticheart valve;

FIG. 6 is a side, partial cross-sectional view of one embodiment of adelivery system of the invention for implanting a balloon-expandablestent of a replacement prosthetic heart valve;

FIGS. 7-10 are sequential perspective views of the implantation of aself-expanding stent in a prosthetic heart valve, utilizing a retrogradeapproach of implantation;

FIG. 11 is a perspective view of a prosthetic heart valve with anotherexemplary embodiment of a stent of a replacement prosthetic heart valveof the invention positioned therein;

FIG. 12 is a top view of the stent of FIG. 11 as positioned relative tothe outflow end of a prosthetic heart valve;

FIG. 13 is a bottom view of the stent of FIG. 11 as positioned relativeto the inflow end of a prosthetic heart valve;

FIG. 14 is a perspective view of the stent of FIG. 11 as it can be usedas a component of a replacement prosthetic heart valve;

FIG. 15 is a side view of the stent and prosthetic heart valve of FIG.11;

FIG. 16 is a perspective view of another exemplary embodiment of a stentof a replacement heart valve of the invention, with the stent in apartially compressed state;

FIG. 17 is a perspective view of the stent of FIG. 16 positioned withina prosthetic heart valve;

FIG. 18 is a side view of the stent and heart valve of FIG. 17;

FIG. 19 is a top view of the stent of FIG. 16 as positioned relative tothe outflow end of a prosthetic heart valve, with the stent in itsexpanded state;

FIG. 20 is a bottom view of the stent of FIG. 16 as positioned relativeto the inflow end of a prosthetic heart valve, with the stent in itsexpanded state;

FIG. 21 is a perspective view of the stent of FIG. 16 in its expandedstate;

FIG. 22 is a perspective view of the stent of FIGS. 16-21 as positionedrelative to a prosthetic heart valve;

FIG. 23 is a perspective view of another exemplary embodiment of a stentof a replacement valve of the invention, positioned within a prostheticheart valve;

FIG. 24 is a perspective view of the stent of FIG. 23;

FIG. 25 is a perspective view of another exemplary embodiment of a stentof a replacement valve of the invention, positioned within a prostheticheart valve;

FIG. 26 is a top view of the stent of FIG. 25 as positioned relative tothe outflow end of a prosthetic heart valve;

FIG. 27 is a bottom view of the stent of FIG. 25 as positioned relativeto the inflow end of a prosthetic heart valve;

FIG. 28 is a perspective view of the stent of FIG. 25;

FIG. 29 is a side view of the stent of FIG. 28 positioned relative to aprosthetic heart valve;

FIG. 30 is a perspective view of another exemplary embodiment of a stentof a replacement valve of the invention positioned within a prostheticheart valve;

FIG. 31 is a top view of the stent of FIG. 30, as positioned relative tothe outflow end of a prosthetic heart valve;

FIG. 32 is a bottom view of the stent of FIG. 30, as positioned relativeto the inflow end of a prosthetic heart valve;

FIG. 33 is a perspective view of the stent of FIG. 30;

FIG. 34 is a side view of the stent positioned within a prosthetic heartvalve of FIG. 30;

FIG. 35 is a perspective view of another exemplary embodiment of a stentof a replacement valve of the invention positioned within a prostheticheart valve, with the stent in its partially compressed state;

FIG. 36 is a perspective view of the stent of FIG. 35 in its partiallycompressed state;

FIG. 37 is a side view of the stent positioned within a prosthetic heartvalve of FIG. 35;

FIG. 38 is a perspective view of the stent of FIGS. 35-37 positionedwithin a prosthetic heart valve, with the stent in its expanded state;

FIG. 39 is a perspective view of the stent of FIG. 38;

FIG. 40 is a top view of the stent of FIG. 38, as positioned relative tothe outflow end of a prosthetic heart valve;

FIG. 41 is a bottom view of the stent of FIG. 38, as positioned relativeto the inflow end of a prosthetic heart valve;

FIG. 42 is a perspective view of another exemplary embodiment of a stentof a replacement valve of the invention positioned within a prostheticheart valve;

FIG. 43 is a perspective view of the stent of FIG. 42;

FIG. 44 is a top view of the stent of FIG. 42, as positioned relative tothe outflow end of a prosthetic heart valve;

FIG. 45 is a bottom view of the stent of FIG. 42, as positioned relativeto the inflow end of a prosthetic heart valve;

FIG. 46 is a perspective view of another exemplary embodiment of a stentof a replacement valve positioned within a prosthetic heart valve, withthe stent in its partially compressed state;

FIG. 47 is a perspective view of the stent of FIG. 46;

FIG. 48 is a top view of the stent of FIG. 47 positioned within aprosthetic heart valve, with the stent in its partially compressedstate;

FIG. 49 is a perspective view of the stent of FIG. 47 in its expandedstate as positioned within a prosthetic heart valve;

FIG. 50 is a perspective view of the stent of FIG. 47 in its expandedstate; and

FIGS. 51 and 52 are perspective views of a prosthetic heart valve with astent of a replacement prosthetic heart valve of the inventionpositioned therein, where FIG. 52 also shows the leaflets of theoriginal prosthetic heart valve.

DETAILED DESCRIPTION

Referring now to the Figures, wherein the components are labeled withlike numerals throughout the several Figures, and initially to FIG. 1, aprosthetic heart valve 10 is illustrated with a stent 30 of theinvention positioned therein, which will be described in further detailbelow. However, referring specifically to the prosthetic heart valve 10,this valve 10 is a typical configuration of a valve that can beimplanted within the heart of a patient, such as by suturing orotherwise securing the valve 10 into the area of a native heart valve ofa patient. The native heart valves referred to herein can be any of thehuman heart valves (i.e., mitral valve, tricuspid valve, aortic valve,or pulmonary valve), wherein the type and orientation of an implanted(e.g., surgically implanted) prosthetic heart valve 10 will correspondwith the particular form, shape, and function of the native heart valvein which it is implanted. Although valve 10 would typically includemultiple leaflets attached within its interior area, such leaflets arenot shown in many of the illustrated embodiments for clarity purposes.

Valve 10 generally includes a valve structure 12 including a stent ring14 from which three stent posts or commissure posts 16 extend. All or aportion of the valve structure 12, including the stent ring 14 and stentposts 16, can be covered by a flexible covering 18, which may be atissue, polymer, fabric, cloth material, or the like to which leaflets(not shown) of the heart valve 10 are attached, such as by sewing.Further, as is known in the art, the internal structure of each of thestent posts 16 can be formed of a stiff but somewhat resilientlybendable material. This construction allows the stent posts 16 to bemoved from the orientation shown in FIG. 1 to a deflected orientation bythe application of an external force. Once this external force isremoved or reduced, the stent posts 16 can then move back toward theorientation shown in FIG. 1.

The valve structure 12 is generally tubular in shape, defining aninternal area 20 (referenced generally) that extends from an inflow end22 to an outflow end 24. The internal area 20 is essentially surroundedby the valve structure 12, and the leaflets attached within the valvestructure 12 selectively allow for fluid flow into or out of the lumenof the natural heart valve in which it is implanted. That is, theinternal area 20 is alternatively open and closed to the lumen of thenatural heart valve in which it is inserted via movement of leaflets. Insome patients, the prosthetic heart valve 10 will have previously beenimplanted in a patient using typical surgical techniques, whereby thestent ring 14 is sewn or attached to the annulus or valvular rim of thenative heart valve. Alternatively, the prosthetic valve could have beenpreviously placed in the patient using minimally invasive techniques forholding the valve in place, such as U-clips, for example, or a widevariety of other techniques and features used for minimally invasiveand/or percutaneous implantation of the initial prosthetic heart valve.

The prosthetic heart valves (e.g., heart valve 10) used in accordancewith the devices and methods of the invention may include a wide varietyof different configurations, such as a prosthetic heart valve that hastissue leaflets, or a synthetic heart valve that has polymeric leaflets.In this way, the prosthetic heart valves can be specifically configuredfor replacing any heart valve. That is, while much of the descriptionherein refers to replacement of aortic valves, the stents (and theirassociated leaflets) of the invention can also generally be used forreplacement of tricuspid valves, for use as a venous valve, or toreplace a failed bioprosthesis, such as in the area of an aortic valveor mitral valve, for example. The replacement prosthetic heart valves ofthe present invention can be employed to functionally replace stentlessprosthetic heart valves as well.

The replacement prosthetic heart valves of the present invention canfacilitate an implantation technique whereby a replacement prostheticheart valve is situated or placed relative to a previously implantedprosthetic heart valve, which may be configured as the heart valve 10shown and described herein. This would become a desirable procedure incases where it is determined that a previously implanted prostheticheart valve is functionally deficient due to one or more of a variety offactors, such as stenosis, valve failure, inflammation, native valveinsufficiency, etc. Regardless of the cause of the deficiency, ratherthan removing the previously implanted prosthetic heart valve andimplanting a second, similarly formed prosthetic heart valve viarelatively complicated and invasive open heart surgical techniques, themethods and devices of the present invention leave the deficientpreviously implanted prosthetic heart valve in place, and deploy the newprosthetic heart valve so that it functionally replaces the previouslyimplanted prosthetic heart valve. Prior to implanting the new prostheticvalve, the leaflets of the previously implanted and deficient prostheticheart valve can either be removed using a variety of techniques such ascutters, lasers, and the like, or the leaflets may instead be left inplace within the deficient valve, where they will likely be pushedtoward the walls of the vessel upon implantation of the new valve.

One embodiment of a stent 30, which can be used as a component of aprosthetic heart valve in accordance with the present invention, isshown in FIGS. 1-4. Stent 30 includes a support structure 31 comprisinga number of strut or wire portions arranged relative to each other toprovide secure coupling between the stent 30 and a prosthetic heartvalve 10 in which it is located. In addition, stent 30 provides asemi-rigid frame for the leaflets of the replacement heart valve, whichwill be attached in some way within the interior portion of stent 30.For ease and clarity of illustration, the leaflets associated with thereplacement heart valves of the invention are not shown in theembodiments of the stents of the invention illustrated herein. Detailsof several configurations of the stents of the invention are describedbelow; however, in general terms, the stents of the invention aregenerally a series of wires arranged into a tubular support structure,and leaflets can be secured to the interior of the support structure.The leaflets can be formed from a variety of materials, such asautologous tissue, xenograph material, synthetics, or the like, as knownin the art. The leaflets may be provided as a homogenous, biologicalvalve structure, such as a porcine, bovine, or equine valve.Alternatively, the leaflets can be provided independent of one another(e.g., bovine or equine pericardial leaflets) and subsequently assembledand attached to a stent support structure. The support structures shownand described relative to the Figures are generally configured toaccommodate three leaflets and replace a heart valve (e.g., heart valve10) that has three commissure posts that accommodate a three-leafletstructure. However, the replacement prosthetic heart valves of theinvention can incorporate more or less than three leaflets.

In more general terms, the combination of a support structure with oneor more leaflets can assume a variety of other configurations thatdiffer from those shown and described, including any known prostheticheart valve design. In one embodiment, a stent support structure withleaflets can be any known expandable prosthetic heart valveconfiguration, whether balloon expandable, self-expanding, or unfurling(as described, for example, in U.S. Pat. Nos. 3,671,979; 4,056,854;4,994,077; 5,332,402; 5,370,685; 5,397,351; 5,554,185; 5,855,601; and6,168,614; U.S. Patent Application Publication No. 2004/0034411;Bonhoeffer P., et al., “Percutaneous Insertion of the Pulmonary Valve”,Pediatric Cardiology, 2002; 39:1664-1669; Andersen H R, et al.,“Transluminal Implantation of Artificial Heart Valves”, EUR Heart J.,1992; 13:704-708; Andersen, H. R., et al., “Transluminal CatheterImplantation of New Expandable Artificial Cardiac Valve”, EUR Heart J.,1990, 11: (Suppl) 224a; Hilbert S. L., “Evaluation of ExplantedPolyurethane Trileaflet Cardiac Valve Prosthesis”, J ThoracCardiovascular Surgery, 1989; 94:419-29; Block P C, “Clinical andHemodyamic Follow-Up After Percutaneous Aortic Valvuloplasty in theElderly”, The American Journal of Cardiology, Vol. 62, Oct. 1, 1998;Boudjemline, Y., “Steps Toward Percutaneous Aortic Valve Replacement”,Circulation, 2002; 105:775-558; Bonhoeffer, P., “TranscatheterImplantation of a Bovine Valve in Pulmonary Position, a Lamb Study”,Circulation, 2000:102:813-816; Boudjemline, Y., “PercutaneousImplantation of a Valve in the Descending Aorta In Lambs”, EUR Heart J.2002; 23:1045-1049; and Kulkinski, D., “Future Horizons in SurgicalAortic Valve Replacement: Lessons Learned During the Early Stages ofDeveloping a Transluminal Implantation Technique”, ASAIO J, 2004;50:364-68).

Referring again to FIGS. 1-4, the stent 30 comprises a support structure31 that is made up of a number of struts or wire segments arranged toprovide desired docking or engagement features. As will be described infurther detail below, the support structure 31 may either be made up ofa number of individual struts or wire segments arranged and secured toeach other, or the support structure 31 may instead be formed from asingle piece of material (e.g., a tube of material that is machined toprovide the structure shown). With particular regard to FIG. 1, stent 30is positioned within a heart valve 10, which typically would have beenpreviously implanted in a patient. Stent 30 comprises a supportstructure 31 having multiple upper vertical members 32 spaced apart fromeach other around the perimeter of the support structure 31, and acorresponding number of lower vertical members 34. Both the upper andlower vertical members 32, 34 extend in a direction that is generallyparallel to a longitudinal axis 40 of the support structure 31, and helpto define the generally cylindrical shape of the support structure 31.Upper vertical members 32 extend generally toward the outflow end 24 ofthe valve structure 12, and the lower vertical members 34 extend in adirection that is generally opposite to the direction of the uppervertical members 32, which is toward the inflow end 22 of the valvestructure 12.

Each of these upper and lower vertical members 32, 34 are preferablyspaced from adjacent upper and lower vertical members 32, 34,respectively, by a distance that is similar or identical to the distancethat the stent posts (e.g., stent posts 16) are spaced from each otherin a corresponding implanted heart valve (e.g., heart valve 10). Thus,both the number of upper vertical members 32 and the number of lowervertical members 34 are typically the same as the number of stent posts.However, it is possible that the number of upper and lower verticalmembers 32, 34 are not the same as each other and/or not the same as thenumber of stent posts.

The upper vertical members 32 are designed to have a height that allowsthem to have a desired amount of contact with a corresponding stentpost. The upper vertical members 32 may extend at least slightly beyondthe tops of the stent posts, or may be at least slightly shorter thanthe stent posts. The lower vertical members 34 may also have any lengththat allows them to have a desired amount of contact with theircorresponding stent posts 16 and other portions of the stent structure12 with which they come into contact. Again, the lower vertical members34 may extend at least slightly below the bottom of the stent structure(i.e., stent ring 14 of FIG. 1), or may be at least slightly shorter sothat they do not extend below any portion of the stent structure. Theselection of the length of these upper and lower vertical members 32, 34can vary widely, depending on the configuration of the valve structureand the amount of contact desired between the support structure 31 andthe interior portion of the stent or valve structure. In any case, theheight of upper and lower vertical members 32, 34 should be adequate toprovide sufficient contact between the support structure 31 and thecorresponding heart valve in which it is positioned to keep the stent 30in place relative to the heart valve. In addition, the arrangement ofupper and lower vertical members 32, 34 should provide sufficientstructural integrity to the support structure 31 so that it is resistantto deformation or other changes that impact its effectiveness as a stentstructure.

The upper and lower vertical members 32, 34 may be generally “U” or “V”shaped, as illustrated, with the distance between opposite “legs” orextending portions of the members being chosen to provide desiredcharacteristics to the support structure 31. For example, in FIG. 1, theupper vertical members 32 are preferably narrow enough that they willnot unintentionally engage with the top edge of corresponding stentposts 16, but are preferably wide enough that they provide adequatecontact with the interior portion of the stent posts 16 to help keep thestent 30 in place. In other words, the distance between opposite legs ofthe “U” or “V” shaped structure is preferably not so large that themembers 32 can latch onto the stent posts 16, but is preferably largeenough to provide contact between the members 32 and some portion of theinterior surface of the stent posts 16. This “U” or “V” shaped structureof these members 32, 34 is particularly adaptable to the configurationwhere the support structure 31 is essentially a continuous wirestructure; however, if the support structure is configured in anothermanner (e.g., with separate components that are not wire-like), each ofthe members 32, 34 may essentially consist of a single, relatively solidextending structure, for example. These structures may be arranged andconnected relative to each other in a similar configuration to thatdescribed relative to a wire structure.

As shown in FIG. 1, heart valve 10 includes three stent posts 16 thatare spaced generally at an equal distance from each other around theperimeter of the valve 10 (i.e., approximately 120 degrees apart). Thesestent posts 16 will generally correspond with the commissures ofleaflets of the valve (not shown). It is understood, however, that thestent posts 16 may instead be unevenly spaced from each other. In oneexample of such an embodiment, first and second stent posts 16 may bespaced from each other by approximately 120 degrees, second and thirdstent posts 16 may be spaced from each other by approximately 115degrees, so that first and third stent posts 16 would be spaced fromeach other by approximately 125 degrees. Other arrangements that varyslightly or substantially from this arrangement may alternatively beused; particularly in cases where more or less than two stent posts 16are used. One example of such an arrangement would be in the case of atwo-leaflet valve (e.g., the mitral valve), which would only include twostent posts arranged at approximately 180 degrees from each other and acorresponding arrangement for its support structure 31.

Support structure 31 further includes multiple upper flange or petalportions 36, each of which is located generally between two adjacentupper vertical members 32, and multiple lower flange or petal portions38, each of which is located generally between two adjacent lowervertical members 34. As is best shown in FIG. 4, the upper and lowerflange portions 36, 38 both extend from a common area 42 of the supportstructure 31, which generally corresponds with the area where the upperand lower vertical members 32, 34 meet. However, the upper and lowerflange portions 36, 38 may instead extend from the vertical members 32,34 at locations that are spaced further from each other. In any case,the upper and lower flange portions 36, 38 are provided for engagementwith the stent or valve structure 12 on generally opposite edges (i.e.,top and bottom edges) of the stent ring 14 when positioned within aheart valve 10. That is, the upper flange portions 36 will be positionedin the area between adjacent stent posts 16 on the outflow end 24 of thevalve structure 12, and the lower flange portions 38 will be positionedgenerally below the upper flange portions 36, but on the opposite sideof the valve structure 12 (i.e., along the bottom edge of the stent ring14 on the inflow end 22 of the valve structure 12).

Orientation and positioning of the stents of the invention may beaccomplished either by self-orientation of the stents (such as byinterference between features of the stent and a previously implantedstent or valve structure) or by manual orientation of the stent to alignits features with anatomical or previous bioprosthetic features, such ascan be accomplished using fluoroscopic visualization techniques, forexample. For example, when aligning the stents of the invention with apreviously implanted bioprosthetic valve, features of the stents canalign with the stent rail and/or commissures of the valve. It isdesirable that the stents be locked in place both rotationally andaxially.

Referring again to FIGS. 1-4, the length and shape of each of theseupper and lower flange portions 36, 38 can be the same or different fromeach other within a single support structure 31, as desired. Forexample, if the stent posts of a corresponding heart valve are spacedevenly from each other, it may be desirable for the flange portions tobe identically spaced, although they may be different from each other insize and/or shape. In any case, it is desirable for the upper and lowerflange portions 36, 38 to extend at least slightly beyond the outerperimeter of the valve structure 12 when the stent is deployed in orderto insure adequate contact between the valve structure 12 and the stent30. However, the amount of extension of the upper and lower flangesbeyond the outer surface of the valve structure 12 should not be solarge that it interferes with any surrounding structure of the heart, aswill be discussed in further detail below.

The upper and lower flange portions 36, 38 may be generally “U” or “V”shaped, as illustrated, although the distance between opposite “legs” orextending portions of the members will generally be larger than thedistance between the legs of the upper and lower vertical members 32, 34within the same stent 30, particularly when the stent 30 is in itsexpanded state. Each upper flange portion 36 includes a distal tip 44and each lower flange member 38 includes a distal tip 46. The tips 44,46 may have a tighter curvature than the rest of their respective flangeportions 36, 38, if desired. In any case, the tips 44, 46 preferablywill contact the upper and lower edges of a stent ring of a heart valvewhen implanted therein. The tips 44, 46 may also serve as interfaces orconnecting portions with a corresponding delivery system, as will beexplained in further detail below.

The lower flange portions 38 are configured to engage with the lowersurface of a sewing ring 14 of a previously implanted prosthetic heartvalve (e.g., heart valve 10) when the stent 30 is in its expandedcondition. Alternatively, the lower flange portions 38 can be configuredto engage other structure(s) of the previously implanted prostheticheart valve. Referring to FIG. 1, in order to engage with a previouslyimplanted heart valve, one exemplary embodiment of a lower flangeportion 38 includes a wire structure that extends generally from acommon area 42 on one upper vertical member 32 toward the tip 46 of theflange portion 38, then toward another common area 42 on an adjacentupper vertical member 32. The curvature or contours of each flangeportion 38 can be designed so that it closely matches the shape of thestent or valve structure 12 in which it will be implanted, such as atits inflow end 22. That is, there is preferably minimal to no gapbetween the flange 38 and the interior surface of the valve structure12.

As shown in FIG. 3, each of the tips 46 of the flange portions 38 arepositioned approximately 120 degrees from each other around theperiphery of the sewing ring 14, although they can be spaced differentlyfrom each other, depending on the locations of the stent posts of theheart valve. When the stent 30 is in an expanded condition, the lowerflange portions 38 are preferably biased toward the sewing ring 14 tokeep the flange portion 38 in place relative to the heart valve 10.

The upper flange portions 36 are configured to engage with the spacesbetween stent posts 16 of a previously implanted heart valve (e.g.,heart valve 10) when the stent 30 is in its expanded condition.Alternatively, the upper flange portions 36 can be configured to engageother structure(s) of the previously implanted prosthetic heart valve.Referring to FIG. 1, in order to engage with a previously implantedheart valve, one exemplary embodiment of an upper flange portion 36includes a wire structure that extends generally from a common area 42on one upper vertical member 32 toward the tip 44 of the flange portion36, then toward another common area 42 on an adjacent vertical member32. The curvature or contours of each flange portion 36 can be designedto closely match the shape of the stent or valve structure 12 in whichit will be implanted. As shown in FIG. 2, each of the tips 44 of theflange portions 36 are positioned approximately 120 degrees from eachother around the periphery of the sewing ring 14, although they can bespaced differently from each other, depending on the locations of thestent posts of the heart valve. In any case, the tip 44 of flangeportion 36 will preferably fit between adjacent stent posts 16 in orderto help physically dock or connect the stent 30 to the previouslyimplanted heart valve 10. When the stent 30 is in an expanded condition,the upper flange portions 36 are preferably biased toward the sewingring 14 (and preferably toward a corresponding lower flange portion 38)to keep each flange portion 36 in place relative to the heart valve 10.

The support structure 31 of the stent 30 is, in one embodiment, a wirestent capable of transitioning from a collapsed state to an expandedstate, where a number of individual wires comprising the supportstructure 31 are formed of a metal or other material. These wires arearranged in such a way that a support structure 31 is provided thatallows for folding or compressing to a contracted state in which itsinternal diameter is at least somewhat smaller than its internaldiameter in an expanded state. In its contracted state, such a supportstructure 31 with attached valves can be mounted relative to a deliverydevice, such as a balloon catheter, for example. The support structure31 is configured so that it can be changed to its expanded state whendesired, such as by the expansion of a balloon catheter. The deliverysystems used for such replacement heart valve can optionally be providedwith degrees of rotational and axial orientation capabilities in orderto properly position the new heart valve within the previously implantedheart valve.

The wires of the support structure 31 can alternatively be formed from ashape memory material such as a nickel titanium alloy (e.g., Nitinol).With this configuration, the support structure 31 is self-expandablefrom a contracted state to an expanded state, such as by the applicationof heat, energy, and the like, or by the removal of external forces(e.g., compressive forces). In addition, the support structure 31 ofthis embodiment may be laser cut from a single piece of material or maybe assembled from a number of different components. For these types ofstent structures, one example of a delivery system that can be usedincludes a catheter with a retractable sheath that covers a compressedstent (thereby providing external compressive forces on the stent) untilit is to be deployed, at which point the sheath can be retracted toallow the stent to expand.

The support structure 31 can include features not specifically describedor shown instead of, or in addition to, the various coupling structuresand methods described herein. For example, the support structure 31 canhave a non-expandable design, but can instead be sized and shaped tonest within a previously implanted heart valve (not shown) in a mannerthat presses features of the previously implanted heart valve (e.g.,leaflets) outwardly relative to the native conduit.

The height and diameter of the stent 30 in its expanded state ispreferably chosen and/or designed for use with a previously implantedprosthetic heart valve having a particular size and shape. Thus, thestent 30 can assume a variety of different longitudinal heights and/ordiameters. In one embodiment, for example, the support structure 31 hasa height in its expanded state that is slightly greater than a height ofthe previously implanted prosthetic heart valve, and/or has afree-standing outer diameter that is greater than an inner diameter ofthe previously implanted prosthetic heart valve. With this embodiment,upon transitioning toward the expanded state, the support structure 31(including the vertical members 32, 34) presses against an innerdiameter of the previously implanted prosthetic heart valve. The overallshape of the support structure 31 is cylindrical in many cases; however,other shapes are also contemplated, such as elliptical, oval, or thelike. For example, portions of the support structure 31 can define anenlarged diameter as compared to other portions. Further, depending uponthe previously implanted heart valve being functionally replaced, thesupport structure 31 can be less uniform along a height thereof.

One method of delivering the stent 30 to the location of a previouslyimplanted heart valve (e.g., heart valve 10) is performedpercutaneously, as represented in simplified form in FIG. 6. In generalterms for this exemplary delivery system, a transcatheter assembly 70 isprovided, including a delivery catheter 72, a balloon catheter 74, and aguide wire 76. The delivery catheter 72 is of a type known in the art,and defines a lumen 78 within which the balloon catheter 74 is received.The balloon catheter 74, in turn, defines a lumen (not shown) withinwhich the guide wire 76 is slidably disposed. Further, the ballooncatheter 74 includes a balloon 80 that is fluidly connected to aninflation source (not shown). It is noted that if the stent beingimplanted is a self-expanding type of stent, the balloon would not beneeded and a sheath or other restraining means would instead be used formaintaining the stent in its compressed state until deployment of thestent. In any case, in this embodiment, the transcatheter assembly 70 isappropriately sized for a desired percutaneous approach to theprosthetic heart valve 10 that was previously implanted in a nativeheart valve 79. For example, the transcatheter assembly 70 can be sizedfor delivery to the heart valve 10 via an opening at a carotid artery, ajugular vein, a sub-clavian vein, femoral artery or vein, or the like.Essentially, any percutaneous intercostals penetration can be made tofacilitate use of the transcatheter assembly 70.

Prior to delivery, the stent 30 is mounted over the balloon 80 in acontracted state to be as small as possible without causing permanentdeformation of the stent structure. As compared to the expanded state,the support structure 31 is compressed onto itself and the balloon 80,thus defining a decreased inner diameter as compared to an innerdiameter in the expanded state. Further, the vertical members 32, 34 andflange portions 36, 38 are compressed toward the longitudinal axis 40when in the contracted state. While this description is related to thedelivery of a balloon-expandable stent, the same basic procedures canalso be applicable to a self-expanding stent, where the delivery systemwould not include a balloon, but would preferably include a sheath orsome other type of configuration for maintaining the stent in itscompressed condition until its deployment.

With the stent 30 mounted to the balloon 80, the transcatheter assembly70 is delivered through a percutaneous opening (not shown) in thepatient via the delivery catheter 72. The previously implanted heartvalve 10 is located by inserting the guide wire 76 into the patient,which guide wire 76 extends from a distal end 82 of the deliverycatheter 72, with the balloon catheter 74 otherwise retracted within thedelivery catheter 72. Once the previously implanted heart valve 10 hasbeen located, the balloon catheter 74 is advanced distally from thedelivery catheter 72 along the guide wire 76, with the balloon 80 andstent 30 positioned relative to the previously implanted heart valve 10.More particularly, the balloon 80 and stent 30 are positioned within theinternal region of the previously implanted prosthetic heart valve 10,with the lower flange portions 38 positioned adjacent the sewing ring 14of the heart valve 10, and the upper flange portions 36 are positionedadjacent the outflow end 24 of the previously implanted prosthetic heartvalve 10.

In an alternative embodiment, the stent 30 is delivered to thepreviously implanted prosthetic heart valve 10 via a minimally invasivesurgical incision (i.e., non-percutaneously). In another alternativeembodiment, the stent 30 is delivered via open heart/chest surgery.Regardless, with the stent 30 in the contracted state, the supportstructure 31 can readily move within the internal area 20 of thepreviously implanted prosthetic heart valve 10, and the vertical members32, 34 and flange portions 36, 38, which are otherwise retracted orcompressed, do not unintentionally contact or engage portions of thepreviously implanted prosthetic heart valve 10. In one embodiment, thestent 30 includes a radiopaque, echogenic, or MRI visible material tofacilitate visual confirmation of proper placement of the stent 30relative to the previously implanted prosthetic heart valve 10.Alternatively, other known surgical visual aids can be incorporated intothe stent 30.

The techniques described above relative to placement of the stent 30within the heart can be used both to monitor and correct the placementof the stent 30 in a longitudinal direction relative to the length ofthe anatomical structure in which it is positioned and also to monitorand correct the orientation of the stent 30 relative to the stent posts16 of the previously implanted heart valve 10. In particular, it isdesirable for the stent 30 to be positioned so that each of the upperflange portions 36 are between two adjacent stent posts 16 when they areexpanded outwardly.

Once the stent 30 is properly positioned, the balloon catheter 74 isoperated to inflate the balloon 80, thus transitioning the stent 30 tothe expanded state shown in FIG. 1. Alternatively, if the supportstructure 31 is formed of a shape memory material, the stent can beallowed to self-expand to the expanded state of FIG. 1. Thus, aself-expanding stent structure can be percutaneously delivered by anappropriate catheter device other than a balloon catheter, as will bedescribed in further detail below. In either case, the support structure31 expands within the internal region 20 of the previously implantedheart valve 10, radially pressing against the valve structure 12.Because the previously implanted prosthetic heart valve 10 would haveincluded leaflets (not shown), radial expansion of the stent 30 wouldpress against these leaflets, thereby lodging them against the valvestructure 12.

FIG. 5 illustrates an exemplary embodiment of a stent 50 that includes anumber of eyelets or apertures 52 that can be used for maintaining thevarious components of stent 50 in a compressed state when desired. Theseeyelets 52 would be particularly useful in the case where the stent 50is a self-expanding stent, since this type of structure needs externalforces to keep it in its compressed state. In particular, an eyelet 52may be located at the end of at least one of the multiple upper verticalmembers 54 and/or one or more of the upper and lower flange portions 56,58 and the lower vertical members 55. Each eyelet 52 is preferably sizedfor accepting an elongated thread-like material, such as suture materialor a thin wire, and/or sized for engagement with a hook or otherengagement feature of a delivery device. If a thread-like material isused, it can be threaded through at least one of the eyelets 52 in sucha way that when the material is pulled tight, the eyelets 52 are pulledtoward the central axis of the stent 50. If a wire-like material isused, it may be configured as a metal snare or other configuration thatpulls the eyelets 52 toward the central axis of the stent 50. If adelivery device having such engagement features is used, it may beconfigured in such a way that the engagement features can be movedtoward and away from the central axis of the stent, as desired forinsertion and deployment of the stent.

Other arrangements of pulling the various portions of a stent toward acentral stent axis are also contemplated, which preferably arerelatively easy to operate for compression and release of the stentstructures. In any case, once the stent structure is compressed to itsdesired configuration, the feature used to pull the stent into itscompressed configuration is capable of being secured or fastened in someway to keep the stent from unintentionally expanding. This same featurecan have its operation reversed to allow the various structures of thestent to move toward their expanded state.

FIGS. 7-10 illustrate one exemplary system of delivering a stent of thetype illustrated in FIG. 5, for example, into a heart valve 10, whichwould have previously been implanted in a patient. One feature providedby the delivery system of this embodiment is that a self-expanding stentis retrievable after its initial deployment if it is not positionedcorrectly in the heart. The stent then could be redeployed into theproper position, using the same or a different delivery system. Withparticular reference to the Figures, a distal portion of a deliverysystem 90 is illustrated, which includes a tip portion 92 and a sheath94. The system further includes a plurality of hooks or engagementfeatures 96 that can engage with eyelets 52 of stent 50, for example.While this delivery system 90 can generally be used for more proceduresthan the described implantation procedure, the procedure illustratedrelative to FIGS. 7-10 is particularly directed to percutaneous deliveryof a stent to a previously implanted aortic heart valve via a retrogradeapproach. For purposes of this description of an implantation method,the exemplary stent 50 of FIG. 5 is used in the implantationdescription; however, a number of different stent embodiments mayutilize these same procedures, such as other stent embodiments describedrelative to the present invention.

As illustrated in FIG. 7, delivery system 90 is being advanced towardheart valve 10 as such a heart valve would have been previouslyimplanted in a patient. A compressed replacement valve (not shown) isencompassed within sheath 94 for insertion into the patient so thatthere is no contact between the replacement valve and any portion of thepatient's internal anatomy during the insertion process.

FIG. 8 illustrates delivery system 90 as it has been further advancedinto heart valve 10, and wherein the sheath 94 has been partiallyretracted away from the tip 92 to expose the stent 50 that waspreviously compressed therein. Because the upper flange portions 56 wereno longer constrained by the sheath 94, these portions 56 were able tomove away from a central member 100 of the delivery system 90 as thesheath 94 was retracted. Further, eyelets 52 that extend from the endsof upper vertical members 54 are each engaged by a hook 96 of thedelivery system 90. These hooks 96 can be attached to a mechanism withinthe interior portion of the sheath 94, for example, or may be attachedto some other structure that extends through the sheath 94. In eithercase, hooks 96 can maintain the upper vertical members 54 in theircompressed state until they are disengaged from the hooks 96. That is,the delivery system can control the diameter of the stent inflowstructures, the stent outflow structures, or both the stent inflow andoutflow structures independently or together. As is also illustrated inFIG. 8, the lower flange portions 58 are held in their compressed statewith a snare 98 that engages with eyelets 52 that extend from each ofthe flange portions 58. Snare 98 is shown as a single, shaped piece ofelongated material; however, the lower flange portions 58 may instead beheld in their compressed state via an alternative structure or system,such as by a suture, or by a moveable sleeve attached to the deliverysystem, for example.

As shown in FIG. 9, the delivery system 90 is further advanced intovalve 10 until the upper flange portions 56, which are extendingradially away from the central member 100 of the delivery system 90,become engaged with the valve structure 12 of the heart valve 10. Inparticular, each of the upper flange portions 56 are preferablypositioned to be in contact with the surface of the stent ring 14between two adjacent stent posts 16. In order to verify that the flangeportions 56 are properly positioned relative to the valve structure 12(e.g., flange portions 56 are not resting on the top of the stent posts16), the entire delivery system 90 can be rotated slightly in eitherdirection while pressing downwardly toward the valve structure 12. Thesystem 90 can also be advanced axially to the desired position. In thisway, the flange portions 56 can be moved into the area between adjacentstent posts 16 if they are not already in this position.

Once the delivery system 90 and its stent 50 are properly oriented, thesnare 98, sheath, or other structure holding the lower flange portions58 in their compressed state is released or retracted, thereby allowingthe lower flange portions 58 to deploy or radially extend, asillustrated in FIG. 10. The lower flange portions 58 can then contactthe surface of the stent ring 14 that is opposite the surface that iscontacted by the upper flange portions 56. The hooks 96 can then bedisengaged from the eyelets 52 of stent 50, such as by further advancingthe delivery system 90 into the opening of the valve 10, or byactivating a mechanism associated with the hooks 96 that can move thehooks 96 relative to the eyelets 52 until they become disengaged fromthe eyelets 52. It is noted that the stent is retrievable at any pointprior to the hooks 96 being disengaged from the stent 50 with use of thehooks 96 and/or the sheath 94. The upper and lower vertical members 54,55 are then free to expand radially until they contact the inner surfaceof the stent or valve structure 12. The upper and lower vertical members54, 55 preferably are configured so that they will press against theinner surface of the valve structure 12 with sufficient force to providefurther anchoring of the stent 50 within the previously implanted heartvalve 10.

After the stent 50 is implanted and its various portions are deployed orreleased from a compressed state to an expanded state, the deliverysystem 90 can be removed from the patient. The stent 50 will then be inits deployed or expanded state, as is generally illustrated in FIG. 5,or in a similar manner to that illustrated in FIG. 1 relative to a stent30.

FIGS. 11-15 illustrate another exemplary embodiment of a stent 110 thathas a similar structure to the stent 30 of FIG. 1, but further includesat least one stent post engaging structure 112. Relative to the specificembodiment of the stent 110 that is illustrated, this structure alsodoes not include upper flange portions (such as upper flange portions 36of stent 30), since such portions could be redundant and/or interferewith the specific structure of the structures 112 shown. However, it iscontemplated that upper flange portions could also be provided with thisembodiment, if they are configured to not interfere with any stent postengagement structures 112. Further, in the embodiment shown in theFigures, three structures 112 are provided to correspond with a likenumber of stent posts 16 of heart valve 10; however it is contemplatedthat the stent 110 includes less than three structures 112, even ifthree stent posts are provided. If less than three structures 112 areprovided, it may be desirable to additionally provide at least one upperflange portion to engage with the heart valve 10.

Each stent post engaging structure 112 is configured to partiallysurround a portion of a stent post 16, thereby providing another way ofanchoring the stent 110 in place. These structures 112 can cooperatewith one or more lower flange portions 114 to provide anchoring on boththe inflow and outflow ends of the previously implanted heart valve 10.The structures 112 can be individual structures that are each secured toupper vertical members 116, or may be formed as a single structurehaving multiple loops that are secured to the structure of the stent110. Alternatively, these structures 112 can be integrally formed withthe structure of the stent 110. Stent 110 can be a self-expanding stentor may be a balloon-expandable stent structure.

FIGS. 16-22 illustrate another exemplary embodiment of a stent 120 foruse with a replacement prosthetic heart valve in accordance with thepresent invention. Stent 120 includes a number of strut or wire portionsarranged relative to each other to provide secure coupling between thestent 120 and a previously-implanted prosthetic heart valve, such asheart valve 10. In addition, stent 120 provides a semi-rigid frame forthe leaflets of the replacement heart valve, which will be attached tothe interior portion of stent 120, as will be described in furtherdetail below.

Stent 120 includes multiple upper vertical members 122 spaced apart fromeach other around the perimeter of the stent 120, and a correspondingnumber of lower vertical members 124. It is understood that the numberof upper and lower vertical members can be different from each other,however. Both the upper and lower vertical members 122, 124 extend in adirection that is generally parallel to a longitudinal axis of the stent120, thereby partially defining the generally cylindrical shape of thestent 120. Upper vertical members 122 extend generally toward theoutflow end of the stent structure 12, and the lower vertical members124 extend in a direction that is generally opposite to the direction ofthe upper vertical members 122, which is toward the inflow end of thestent structure 12. As with previously described embodiments, the numberof upper and lower vertical members 122, 124 may or may not be the sameas the number of stent posts of the stent structure 12. In addition, thelength of upper and lower vertical members 122, 124 should be adequateto provide sufficient contact between the stent 120 and the stentstructure 12 to help keep the stent 120 in place relative to the heartvalve 10.

Stent 120 further includes upper and lower flange portions 126, 128,respectively. Flange portions 126, 128 are configured for positioning onopposite sides of a stent ring 14 of stent structure 12 when the stentis in its expanded state. Through the design and manufacturing of thestent 120, the flange portions 126, 128 can be biased toward each otherwhen the stent is in its expanded condition in order to keep the stent120 positioned properly relative to the stent structure 12.

Stent 120 includes components that can be made of materials that performdifferently relative to deployment thereof. In particular, a portion ofstent 120 can be expandable from its compressed state via theapplication of an internal radial force (e.g., inflation of a balloon),while another portion of stent 120 can be self-expandable such that theremoval of radial compressive forces will allow that portion of stent120 to expand without application of additional forces. Alternatively,different portions of the stent 120 can be made of different materialsthat are both self-expanding, or of different materials that areexpandable via the application of an internal radial force. Although thecomponents that comprise these two structures can vary, the stent 120illustrated in FIGS. 16-22 includes a first component that is expandablethrough application of a radial force. This component may be made of amaterial such as stainless steel, for example. The first componentincludes the upper vertical members 122, lower vertical members 124, andlower flange portions 128, and can include a number of componentsattached to each other, or can be a single machined piece. This firstcomponent is illustrated in its compressed state in FIGS. 16-18 and inits expanded state in FIGS. 21 and 22. The stent 120 further includes asecond component that is self-expandable and may be made of a shapememory material such as a nickel titanium alloy (e.g., Nitinol). Thissecond component includes the upper flange portions 126 and also asecond lower vertical member 130 that can at least roughly duplicate theshape of the lower vertical member 124 of the first component.

When this stent 120 is implanted into a patient, a sheath or othermechanism will be holding the self-expandable portions of the stent in acompressed state until such a mechanism is retracted or removed, therebyallowing the upper flange portions 126 to extend radially from the stentstructure, as is illustrated in FIG. 17. These upper flange portions 126are preferably positionable between adjacent stent posts of a previouslyimplanted heart valve for proper orientation of the stent 120. Becausethe first component is not made from a self-expandable material, thefirst component of stent 120 will remain in its compressed state, asshown in FIG. 17, until it is expanded radially, such as via expansionby a balloon catheter that is positioned in its central opening. Whenfully inflated, such a balloon will be constrained by the stentstructure 12 along a portion of its length, but portions of the balloonthat are above and below the stent structure 12 can be allowed to expandfurther so that the balloon takes on an “hourglass” type of shape,thereby pressing the lower flange portions 128 outward and under thestent ring 14, as illustrated in FIG. 22. These lower flange portions128 can thereby help to anchor the stent 120 relative to the heart valvein which it is positioned. Thus, FIGS. 21 and 22 illustrate the stent120 in its expanded state, where the upper and lower flange portions126, 128 are positioned on opposite sides of stent ring 14, and wherethe vertical members 122, 124, 130 are positioned adjacent to theinternal portion of stent structure 12.

FIGS. 23 and 24 illustrate another exemplary embodiment of a stent 140for use as a replacement prosthetic heart valve in accordance with theinvention. This stent 140 includes similar structures to that of thestent 30 of FIG. 1; however, stent 140 does not include lower verticalmembers that correspond to and extend in the opposite direction fromupper vertical members 142. Otherwise, stent 140 can include any of thefeatures described above relative to the stents of the invention. Stent140 can be self-expanding or expandable with application of a radialforce, and pericardial tissue or other materials may be attached to itsstructure to provide a prosthetic heart valve.

FIGS. 25-29 illustrate another exemplary embodiment of a stent 150 foruse as a replacement prosthetic heart valve in accordance with thepresent invention. Stent 150 includes similar structures to the stent110 of FIG. 11, including upper vertical members 152 and correspondinglower vertical members 154, stent post engagement structures 156, andlower flange members 158. In an embodiment where the number of stentpost engagement structures 156 is optionally less than the number ofcorresponding stent posts of the previously implanted heart valve, upperflange members may be included on stent 150, if desired. Alternatively,upper flange members may be included on stent 150 in a configurationthat does not interfere with the structures 156.

Stent 150 further includes “W” shaped structures 160 positioned alongthe stent ring 14 between adjacent stent posts 16 in the interior areaof the stent structure 12. Each structure 160 is positioned generallybetween adjacent lower flange members 158 and provides additionalcontact surfaces between the stent 150 and the interior portion of thestent structure 12. In addition, any or all of the structures 160 can beused to hold a leaflet of the failed bioprosthesis against the stentring of the failed bioprosthesis (such as stent ring 14) so that theleaflets of the failed bioprosthesis do not interfere with the valveleaflets of the newly implanted valved stent. That is, it may bedesirable to hold the leaflets of the failed bioprosthesis toward thestent ring in order to minimize the potential for formation of thrombusbetween the failed leaflets and the new leaflets. In addition, holdingthe leaflets against the stent ring can prevent abrasion and/or tearingof the new leaflets that can occur during repeated contact with the oldleaflets. The structures 160 may take a “W” type shape, as shown, or mayinstead have a different shape, such as one or more “U” or “V” shapes, aseries of extensions, a sinusoidal shape, or any desired configurationthat can hold leaflets against the stent ring of the failedbioprosthesis, when desired.

The stent 150 may comprise any desired number of components that areconnected or attached to each other; however, the exemplary embodimentof stent 150 illustrated in FIG. 28 provides an embodiment with twoseparate structures attached or arranged relative to each other. Thatis, a first component is a formed structure that includes the stent postengagement structures 156 and the “W” shaped structures 160, while asecond component is a formed structure that includes the upper and lowervertical members 152, 154 and the lower flange members 158.

FIGS. 30-34 illustrate another exemplary embodiment of a stent 170 foruse as a prosthetic heart valve in accordance with the presentinvention. Stent 170 generally includes upper vertical members 172 andcorresponding lower vertical members 174, upper flange members 176,lower flange members 178, and upper connecting members 182. In thisembodiment, the upper flange members 176 are offset relative to lowerflange members 178 such that each of the upper flange members 176 ispositioned generally between adjacent stent posts 16 of stent structure12, and each of the lower flange members 178 is generally aligned withthe stent posts 16. Upper connecting members 182 extend between adjacentupper vertical members 172 and are provided for tying together the uppervertical members 172 to carry the valve hydrodynamic closing loads,which can thereby reduce various stresses in the stent. The upperconnecting members 182 can also provide interface points for connectionof the stent 170 with the delivery system used for the implantationprocess. Stent 170 further includes optional lower connecting members184 that extend between adjacent lower vertical members 174. Lowerconnecting members 184 are provided for attachment of the material thatmakes up the leaflets of the replacement heart valve. That is,pericardial or another valve material may be sewn or otherwise attachedto the lower connecting members 184 and may further be sewn or otherwiseattached to the upper vertical members 172.

The upper connecting members 182 are shown as a single curved member;however, the connecting members can have any desired structure orconfiguration that provides the desired support for the upper verticalmembers 172. Further, the connecting members 182 may be made of the sameor a different material than the other portions of the stent.

One or more of the lower flange members 178 may further include aneyelet or aperture 180 for engagement with a structure for use duringthe implantation of the stent 170 (e.g., sutures or a hook structurethat can pull the stent structure toward its central axis). One or moreof the upper vertical members 172 may similarly include an eyelet oraperture 185 for use during the implantation of the stent 170 and/or foruse as an anchor point for attachment of valve material to the stent170.

FIGS. 35-41 illustrate another exemplary embodiment of a stent 200 foruse as a replacement prosthetic heart valve in accordance with thepresent invention. Stent 200 is similar to stent 120 of FIG. 16 in thatstent 200 also includes a portion that is made of a material that isexpandable (e.g., stainless steel) with a device such as a ballooncatheter, for example, and a portion that is made of a material that isself-expanding (e.g., Nitinol) when external forces are removed. Inparticular, a self-expanding portion of stent 200 may include upperflange portions 202 that can be generally positioned between adjacentstent posts 16 of a stent structure 12, and bracing portions 204 thatcan be generally aligned with stent posts 16 of a stent structure 12.The other portion (i.e., the portion that is not self-expanding) of thestent 200 may include any or all of the following structures: uppervertical members 206; lower vertical members 208; upper supportstructures 210 extending between adjacent upper vertical members 206;lower support structures 212 extending between adjacent lower verticalmembers 208, lower flange portions 220; and intermediate lower flangeportions 214 located between adjacent lower flange portions 220. Thelower flange portions 214 can provide additional anchoring force for thestent 200 against the stent structure 12 in the areas generally adjacentto the stent posts 16. The lower support structures 212 may be used forsecuring the valve structure to the stent 200, if desired.

FIGS. 42-45 illustrate another exemplary embodiment of a stent 230 foruse as a prosthetic heart valve in accordance with the presentinvention. Stent 230 includes multiple upper vertical members 232 andoptional corresponding lower vertical members 234, and multiple lowerflange members 236. The number of upper vertical members 232 and lowervertical members 234 preferably correspond to the number of stent postsof the previously implanted heart valve. In addition, the number oflower flange members 236 also preferably corresponds to the number ofstent posts 16 of the previously implanted heart valve 10 so that onelower flange member 236 can be positioned generally between two adjacentstent posts 16, but on the opposite side of the stent structure 12 fromthe stent posts 16. The stent 230 further includes multiple upper flangemembers 238, which are positionable in the space between every twoadjacent stent posts 16, but on the same side of the stent structure 12as the stent posts 16. In this embodiment illustrated in FIGS. 42-45,two upper flange members 238 are positioned in each of the spacesbetween two adjacent stent posts 16, which thereby provide additionalanchoring points for the stent 230 within the stent structure 12. Inaddition, these flange members 238 can function similarly to thestructures 160 described above relative to FIGS. 25-29 in that one ormore of the flange members 238 can help to hold the leaflets of thefailed bioprosthesis generally against the stent ring of thebioprosthesis so that they do not interfere with the leaflets of the newvalved stent. The stent 230 can be configured so that each of the upperflange members 238 of the pair of upper flange members are angled atleast slightly toward their adjacent stent posts 16 so that they arefacing in at least slightly opposite directions from each other.

FIGS. 46-50 illustrate another exemplary embodiment of a stent 250 foruse as a prosthetic heart valve in accordance with the invention. Stent250 is similar to stent 120 of FIG. 16 in that stent 250 also includes aportion that is made of an expandable material (e.g., stainless steel)with a balloon catheter, for example, and a portion that is made of amaterial that is self-expanding (e.g., Nitinol) when external forces areremoved. In particular, a self-expanding portion of stent 250 mayinclude multiple stent post engagement structures 252, which are shownin this embodiment as being part of a continuous unit or piece that isconfigured to include three stent post engagement structures 252. Eachof the structures 252 is provided to engage with a stent post 16 of astent structure 12. The other portion (i.e., the portion that is notself-expanding) of the stent 250 comprises a mesh-like stent structure254 that includes a number of wire portions arranged as best illustratedin the expanded version of the stent 250 in FIG. 50. Although thisembodiment does not illustrate particular flange portions that extendabove or below the stent structure 12, it is contemplated that any ofthe anchoring structures discussed above may be incorporated into thestent 250 to provide additional anchoring mechanisms for the stent 250.

FIGS. 51 and 52 illustrate another stent 360 of the invention as it canbe implanted within a previously implanted heart valve, such as a heartvalve 362. FIG. 52 illustrates an exemplary positioning of the leaflets370 of the previously implanted heart valve 362 and FIG. 51 does notshow these leaflets. Stent 360 includes a split petal structure for itsupper flange member that is positioned between stent posts 364, as shownwith petals 366, 368. These petals 366, 368 provide two structures forholding the leaflets 370 of the heart valve 362 against the stent railof that heart valve 362 so that the leaflets 370 do not interfere withthe implantation and/or functioning of the newly implanted heart valve.The petals 366, 368 may have the same configuration as each other, asshown, or may instead be differently sized and/or shaped than eachother. It is also contemplated that other structures may be used, suchas a series of barbs or extending members, and it is further understoodthat more or less than two structures can be used for holding theleaflets 370 against the rail of the heart valve 362. The petalstructures could also be used to hold native leaflets outward for thestented valve implanted in a native valve.

As discussed herein, the various stent embodiments of the invention canall be used with a valve structure for replacement of a previouslyimplanted prosthetic heart valve. A number of different delivery systemscan be used for implantation of such devices, including the deliverysystems described above, along with other exemplary delivery systems,such as those described in U.S. Patent Application Publication No.2003/0199963-A1; U.S. patent application Ser. No. ______, entitled“DELIVERY SYSTEMS AND METHODS OF IMPLANTATION FOR REPLACEMENT PROSTHETICHEART VALVES”, Attorney Docket No. MT10038/US/2 (P0026773.02), filed oneven date herewith; U.S. patent application Ser. No. ______, entitled“DELIVERY SYSTEMS AND METHODS OF IMPLANTATION FOR REPLACEMENT PROSTHETICHEART VALVES”, Attorney Docket No. MT10038/US/3 (P0026773.03), filed oneven date herewith, and U.S. patent application Ser. No. _______,entitled “REPLACEMENT PROSTHETIC HEART VALVES AND METHODS OFIMPLANTATION”, Attorney Docket No. MT10038/US (P0026773.01), filed oneven date herewith, all of which are incorporated by reference in theirentireties.

Referring again to FIG. 1, the stent or valve structure 12 includes asewing ring 14 and stent posts 16 and is covered by a covering 18, suchas is included in the stented tissue valves commercially available fromMedtronic, Inc. of Minneapolis, Minn. under the trade designations“Hancock II” and “Mosaic”. A wide variety of other stented tissuevalves, such as those described in U.S. Pat. Nos. 4,680,031, 4,892,541,and 5,032,128, the teachings of which are incorporated herein byreference, can be employed as the stent or valve structure 12.Alternatively, the structure 12 can be stentless, such as, for example,a Freestyle stentless bioprosthesis, commercially available fromMedtronic, Inc. under the trade designation “Freestyle”. Otheracceptable stentless configurations are described in U.S. Pat. Nos.5,156,621; 5,197,979; 5,336,258; 5,509,930; 6,001,126; 6,254,436;6,342,070; 6,364,905; and 6,558,417, the teachings of which areincorporated herein by reference. Regardless, the leaflets (not shown)are attached to the structure 12 by sewing, crimping, adhesive, etc.,for example, and can assume a variety of forms (e.g., autologous tissue,xenograph tissue, or synthetic material, such as polymers, metals,combinations thereof, and the like).

With any of the embodiments of the invention described herein, thevalved stents can be placed inside of a failed valve with leaflets, asdescribed herein, or the leaflets of the failed valve can be removedprior to implantation of the new valved stents, in accordance with knownprocedures for leaflet removal. Exemplary procedures for leaflet removalare described, for example, in U.S. Patent Publication No. 2004/0034380(Woolfson et al.), and exemplary devices and methods of filtering inconjunction with leaflet removal are described, for example, in U.S.Pat. No. 6,896,690 (Lambrecht et al.) and U.S. Pat. No. 6,692,513(Streeter et al.), all of which are incorporated herein by reference. Inthis way, the leaflets of the failed bioprosthesis cannot interfere withthe leaflets of the newly implanted valved stent and particulates fromthe leaflet removal can be filtered from the blood of the patient.

Stents described herein may further include at least one location of aradiopaque, echogenic, or MRI visible material to facilitate visualconfirmation of proper placement of the stent relative to the previouslyimplanted prosthetic heart valve. Alternatively, other known surgicalvisual aids can be incorporated into the stent. Such visual aids can beincluded on at least one flange of the replacement heart valve and atleast one stent post of the previously implanted heart valve to provideindicators for proper placement of the stent.

It is further noted that the stent embodiments described herein can alsoinclude a tubular structure that is generally positioned within thepreviously implanted heart valve, wherein the various flanges and stentpost engagement features can extend from the body of the tubularstructure. In addition, the stents described herein may include a gasketmaterial around all or a portion of the perimeter to provide forenhanced sealing between the new prosthetic valve and the previouslyimplanted heart valve.

The present invention has now been described with reference to severalembodiments thereof. The foregoing detailed description and exampleshave been given for clarity of understanding only. No unnecessarylimitations are to be understood therefrom. It will be apparent to thoseskilled in the art that many changes can be made in the embodimentsdescribed without departing from the scope of the invention. Thus, thescope of the present invention should not be limited to the structuresdescribed herein, but only by the structures described by the languageof the claims and the equivalents of those structures.

1. A replacement prosthetic heart valve for engagement with a structureof a previously implanted prosthetic heart valve, the replacement heartvalve comprising: a stent structure comprising: a generally tubular bodyportion comprising an interior area and a series of wire portionsarranged in a mesh-like configuration; and at least one stent postengaging structure extending radially outwardly from the body portionfor engaging with an outer surface of a stent post of the previouslyimplanted prosthetic heart valve; and at least two leaflets attachedwithin the interior area of the tubular body portion of the stentstructure.
 2. The replacement heart valve of claim 1, wherein at leastone of the generally tubular body portion and the at least one stentpost engaging structure is self-expandable from a collapsed portion toan expanded position in response to removal of an external compressiveforce.
 3. The replacement heart valve of claim 1, wherein the stentstructure comprises at least one portion that is self-expandable withthe removal of an external compressive force and at least one portionthat is expandable with the application of an outward radial force. 4.The replacement heart valve of claim 3, wherein the tubular body portioncomprises a material that is expandable with the application of anoutward radial force.
 5. The replacement heart valve of claim 4, whereinthe at least one stent post engaging structure comprises aself-expanding material.
 6. The replacement heart valve of claim 1,wherein the stent structure further comprises at least one lower flangemember extending outwardly from the tubular body portion and biasedtoward an outflow end of the replacement heart valve.
 7. The replacementheart valve of claim 1, wherein the stent structure further comprises atleast one upper flange member extending outwardly from the tubular bodyportion and biased toward an inflow end of the replacement heart valve.8. The replacement heart valve of claim 1, wherein at least one stentpost engaging structure comprises a visually detectable marker.
 9. Thereplacement heart valve of claim 1, further comprising a sealing gasketsurrounding at least a portion of a perimeter of the generally tubularbody portion.
 10. A method of implanting a replacement prosthetic heartvalve within a previously implanted prosthetic heart valve, the methodcomprising: positioning a replacement prosthetic heart valve in aninternal area defined by the structure of the previously implantedprosthetic heart valve, wherein the replacement heart valve comprises: astent structure comprising: a generally tubular body portion comprisingan interior area and a series of wire portions arranged in a mesh-likeconfiguration; and at least one stent post engaging structure extendingradially outwardly from the body portion for engaging with an outersurface of a stent post of the previously implanted prosthetic heartvalve; and at least two leaflets attached within the interior area ofthe tubular body portion; wherein a first portion of the stent structureis self-expandable with the removal of an external compressive force anda second portion of the stent structure is expandable with theapplication of an outward radial force; removing the externalcompressive force on the stent structure to allow the first portion ofthe stent structure to radially expand; and applying an outward radialforce to the stent structure to expand the second portion of the stent.11. The method of claim 10, wherein the first portion of the stentstructure comprises the tubular body portion.
 12. The method of claim10, wherein the second portion of the stent structure comprises the atleast one stent post engaging structure.